1. Field of the Invention
The present invention relates to a jacquard circular knitting machine, more specifically to a jacquard circular knitting machine provided with a needle cylinder driving mechanism capable of optionally and readily changing the rotary motion of the needle cylinder of the circular knitting machine according to the pattern to be produced on the fabric.
2. Description of the Related Art
As is well known, a jacquard circular knitting machine such as a hosiery knitting machine includes a cylindrical needle cylinder provided with a plurality of knitting needles, a patterning mechanism for controlling the vertical sliding motion of the knitting needles on the knitting cylinder to knit a jacquard knitted fabric, and a driving mechanism for driving the needle cylinder. Usually, the patterning mechanism employs a pin drum or pin drums for controlling the knitting needles. In recent years, however, computers have been employed in the patterning mechanism. A patterning mechanism employing a computer, namely, a computerized patterning mechanism, has an infinite patterning capacity. That is, by controlling all the individual knitting needles, the computerized patterning mechanism is capable of changing stitches along the wale direction and is capable of producing diversified patterns in the course direction, as compared with the pin drum type patterning mechanism. Furthermore, the computerized patterning mechanism has the advantage that it enables quick and very easy pattern changes without requiring a skilled worker.
On the other hand, in the conventional jacquard circular knitting machine, a driving mechanism, another essential mechanism for the jacquard knitting operation of a jacquard circular knitting machine, of a mechanical type is used. This conventional driving mechanism includes a transmission mechanism for transmitting the driving force of the motor and changing the rotation speed thereof and, for a jacquard hosiery knitting machine, additionally includes a mechanism for changing the direction of rotation of the needle cylinder between the normal direction and the reverse direction, namely, a reversing mechanism. In a circular knitting machine equipped with a reversing mechanism, the needle cylinder is rotated through necessary angles of rotation in the normal and reverse directions according to the pattern to be knitted in the knitting part of the fabric having a pattern, which prevents idle rotation of the needle cylinder. However, changing the revolving rate and the angle of rotation of the needle cylinder according to a pattern to be kntted requires a complex mechanical driving mechanism. Therefore, the circular knitting machine becomes costly and difficult to operate. Even in a conventional jacquard circular knitting machine, which is incapable of the abovementioned additional special performance, it is necessary to replace the sector gear or the equivalent of the reversing mechanism according to a new pattern when changing the pattern, which requires a long time.
Ordinarily, the number of colored yarns which can be stitched into one course is the same as or less than the number of yarn feed units, i.e., the number of knitting stations, provided around the needle cylinder. When a number of colored yarns exceeding the number of the yarn feed units needs to be stitched into one course, one or more of the yarn feed units needs to be equipped with a plurality of yarn feed elements. These yarn feed elements need to be changed a plurality of times during the knitting of one course. A typical pattern which requires such a change of the yarn feed elements is a diamond pattern, i.e., an argyle design, having a stitch pattern. More concretely, a diamond pattern having a stitch pattern is knitted by changing, at a particular knitting station, a yarn feed element for feeding a yarn for knitting the diamond pattern to a yarn feed element, for feeding a yarn for knitting the stitch pattern and, after a predetermined number of stitches has been knitted, by changing the same yarn feed element for feeding the yarn for knitting the stitch pattern to the yarn feed element, for feeding the yarn for knitting the diamond pattern. The mechanism of the conventional jacquard circular knitting machine is incapable of changing the yarn feed elements during a knitting operation with the needle cylinder positioned at any angular position. Accordingly, in order to change the yarn feed elements on a conventional jacquard circular knitting machine, it has been necessary to reverse the direction of rotation of the needle cylinder before changing the yarn feed elements. Namely, for example, the conventional jacquard circular knitting machine has been obliged to knit the diamond pattern and the stitch pattern separately. That is, one course of the diamond pattern having the stitch pattern has been knitted by one full rotation in the normal direction and one full rotation in the reverse direction of the needle cylinder. Accordingly, a time twice as long as the time for knitting only the diamond pattern is required for knitting a diamond pattern having the stitch pattern, with a resultant reduction of production efficiency.